A delay in entering invoice charges is associated with a decrease in total invoice amount in equine practice.

OBJECTIVE: To evaluate the relationship in equine practice between the time delay for charge entry (time between when work was performed and when the invoice charges were entered) and the total amount of the invoice. SAMPLE: A total of 67,597 invoices from 3 hospitals were included for analysis. METHODS: Analysis of 67,597 invoices from 49 doctors working out of 3 hospitals was performed. Variables collected included invoice total, date of work, date of invoice entry, month of work, invoice category (A = ambulatory daytime, E = after-hours, I = hospital), and veterinarian. Time delay to invoice entry was the difference between the day of work and the day of charge entry. A generalized additive model was used to describe the relationship between the time delay for invoice entry and the invoice type, month of work, and invoice category. The best model was selected using the Akaike information criterion. RESULTS: In the selected model, total invoice amount was associated with time delay for charge entry and invoice category. Invoices entered on the same day of work were 299 ± $345, as compared to those entered the next day (255 ± $271) and those entered > 1 day after the work was performed (193 ± $196; P < .0001). CLINICAL RELEVANCE: If the observed relationship between time delay (time between work performed and invoice entry) and total invoice amount is causal, equine practitioners may have significant opportunity to improve revenues by simply entering charges on the same day the work is performed.

Effects of calcium supplementation to resuscitation fluids in endurance horses: A randomized, blinded, clinical trial.

BACKGROUND: The addition of calcium to resuscitation fluids is a common practice in horses, but studies evaluating the effects of calcium supplementation are limited. In healthy horses, decreases in heart rate and changes in serum electrolyte concentrations have been reported. HYPOTHESIS: Calcium gluconate administration at a rate of 0.4 mg/kg/min to eliminated endurance horses with metabolic problems will affect heart rate, gastrointestinal sounds, and serum electrolyte concentrations. ANIMALS: Endurance horses eliminated from the Tevis Cup 100-mile (160 km) endurance ride for metabolic problems and requiring IV fluid therapy were eligible. METHODS: Sixteen horses were randomly assigned to receive 0.4 mg/kg/min of calcium (23% calcium gluconate solution) over 1 hour diluted in 10 L of a non-calcium containing isotonic crystalloid (CAL group) or 10 L of a non-calcium containing isotonic crystalloid (CON group). Staff members administering the fluids were blinded to treatment group. Blood samples were collected and physical examinations performed before and after treatment. Heart rates were recorded every 15 min during fluid administration. Data were compared using 2-way analysis of variance (ANOVA) with repeated measures for continuous variables and Fisher's exact test for categorical variables. RESULTS: Calcium was associated with lower heart rates 45 min after starting the infusion (P = .002). Gastrointestinal sounds were less likely to improve in the calcium group compared with the control group (P = .005). An increase in plasma phosphorus concentration (P = .03) was associated with calcium administration. CONCLUSIONS: Intravenous calcium supplementation to endurance horses eliminated from competition after development of metabolic problems may decrease heart rate but impairs improvement in gastrointestinal sounds.

Changes in electrolyte concentrations and hydration status in endurance horses following transport and an overnight stay prior to competition.

OBJECTIVE: To evaluate changes in electrolyte concentrations and hydration status that take place in endurance horses prior to the start of a competition and determine whether these changes would be associated with elimination. ANIMALS: 19 horses entered in the 2016 Tevis Cup 100-Miles (160 km) One-Day Western States Trail Ride. PROCEDURES: Heparinized blood samples were collected at 5 time points: prior to transport to the ride (T0), during check-in the day before the ride (T1), 1 to 2 hours before the start of the ride (T2), at the 15-km mark (T3), and at the 55-km mark (T4). Packed cell volume and plasma sodium, potassium, chloride, urea nitrogen, glucose, bicarbonate, and total protein concentrations were determined and compared across time points and between finishers and nonfinishers. RESULTS: Signif icant differences were detected among plasma sodium, potassium, and urea nitrogen concentrations measured prior to the start of the ride (ie, T0, T1, and T2). For all variables except chloride and bicarbonate concentrations, significant differences were detected between values obtained prior to the start of the ride and values obtained during the ride (ie, T3 and T4). Only bicarbonate concentration at the 15-km mark of the ride was significantly associated with finishing status. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that significant changes in plasma sodium, potassium, and urea nitrogen concentrations can occur in endurance horses during transport to a competition and when horses are stabled overnight before an event. Additionally, a lower bicarbonate concentration following a steep climb early during the ride was associated with subsequent elimination.

Clinical and biochemical factors associated with survival in equids attacked by dogs: 28 cases (2008-2016).

BACKGROUND: Trauma from dog attacks has been associated with mortality rates as high as 23% in some species. However, the prognosis and clinical features of this type of injury have not been described in equids. HYPOTHESES/OBJECTIVES: To describe survival rate, signalment, clinical features, and biochemical results in equids presented for emergency care after presumed dog attacks. We hypothesized there would be differences between survivors and nonsurvivors. ANIMALS: A total of 28 equids presented for presumed dog attacks from 3 referral centers. METHODS: A retrospective study was performed using data from 3 hospitals between 2008 and 2016. Survival was defined as survival at 14 days postdischarge. Variables were compared between survivors and nonsurvivors using a t test, Mann-Whitney U test, or Fisher's exact test as appropriate. RESULTS: Overall mortality rate was 21%. Ponies and miniature horses represented 16/28 (57%) of the animals in the study. Full-sized equids had a lower risk of nonsurvival as compared to smaller patients (odds ratio = 0.02; 95% confidence intervals = 0.00-0.27; P < .005). Animals with lower body temperatures had increased risk for nonsurvival (P = .0004). Increased admission blood lactate concentrations (P = .003) and decreased serum total protein concentrations (P = .006) were associated with nonsurvival. CONCLUSIONS: The mortality rate in equids attacked by dogs was similar to what is reported for other veterinary species. Smaller equids and those with increased admission blood lactate concentration, lower body temperature, and lower total serum protein concentrations were less likely to survive.

Resolution of neurologic signs presumed to be associated with hyperammonemia in 2 endurance horses.

This case report describes 2 endurance horses with non-hepatic hyperammonemia. The animals were competing in a 160-km endurance competition in extreme heat conditions and were presented for obtundation. One of the horses also had evidence of blindness. The blood ammonia concentration was elevated (196 µmol/L and 249 µmol/L) and both horses improved following treatment with intravenous fluids and supportive care. These are the first documented cases of clinical signs presumed to be associated with hyperammonemia in endurance horses. Despite the severity of the clinical presentation, both horses made a full recovery. Key clinical message: Non-hepatic hyperammonemia should be considered as a potential cause of blindness and obtundation in competing endurance horses. Horses appear to respond well to treatment with intravenous fluids.

Fin des signes neurologiques présumés être associés avec de l'hyperammoniémie chez deux chevaux d'endurance. Le présent rapport de cas décrit la situation de deux chevaux d'endurance avec une hyperammoniémie non-hépatique. Les animaux compétitionnaient dans une course d'endurance de 160 km dans des conditions de chaleur extrême et furent présentés pour confusion. Un des chevaux avait également des évidences de cécité. Les concentrations d'ammoniaque sanguin étaient élevées (196 µmol/L et 249 µmol/L) et les deux chevaux s'améliorèrent à la suite du traitement avec des fluides intraveineux et des soins de support. Ces cas représentent les premiers cas documentés de signes cliniques présumés être associés avec de l'hyperammoniémie chez des chevaux d'endurance. Malgré la sévérité de la présentation clinique, les deux chevaux ont récupéré complètement.Message clinique clé :L'hyperammoniémie non-hépatique devrait être considérée comme une cause potentielle de cécité et de confusion chez des chevaux d'endurance en compétition. Les chevaux semblent bien répondre à un traitement avec des fluides intraveineux.(Traduit par Dr Serge Messier).

Regional anaesthesia practice for arteriovenous fistula formation surgery.

We conducted a survey and semi-structured qualitative interviews to investigate current anaesthetic practice for arteriovenous fistula formation surgery in the UK. Responses were received from 39 out of 59 vascular centres where arteriovenous access surgery is performed, a response rate of 66%. Thirty-five centres reported routine use of brachial plexus blocks, but variation in anaesthetic skill-mix and practice were observed. Interviews were conducted with 19 clinicians from 10 NHS Trusts including anaesthetists, vascular access and renal nurses, surgeons and nephrologists. Thematic analysis identified five key findings: (1) current anaesthetic practice showed that centres could be classified as 'regional anaesthesia dominant' or 'local anaesthesia/mixed'; (2) decision making around mode of anaesthesia highlighted the key role of surgeons as frontline decision makers across both centre types; (3) perceived barriers and facilitators of regional block use included clinicians' beliefs and preferences, resource considerations and patients' treatment preferences; (4) anaesthetists' preference for supraclavicular blocks emerged, alongside acknowledgement of varied practice; (5) there was widespread support for a future randomised controlled trial, although clinician equipoise issues and logistical/resource-related concerns were viewed as potential challenges. The use of regional anaesthesia for arteriovenous fistula formation in the UK is varied and influenced by a multitude of factors. Despite the availability of anaesthetists capable of performing regional blocks, there are other limiting factors that influence the routine use of this technique. The study also highlighted the perceived need for a large multicentre, randomised controlled trial to provide an evidence base to inform current practice.

The Effect of a 160-Kilometer Competitive Endurance Ride on Inflammatory Marker mRNA Expression in Horses.

Previous work to evaluate various risk factors for failure to complete competitive endurance rides has examined clinicopathologic parameters, measurements of inflammation, and speed. Here, inflammatory markers were measured before, during, and after a long-distance, competitive endurance ride to examine the intraride dynamics of inflammatory marker expression and attempt to correlate those findings with whether a horse completed or failed to complete the ride. A total of 77 horses entered into the 2018 Tevis Cup Ride in California were enrolled in the study. Peripheral blood samples for mRNA isolation and gene expression analysis for ALOX5AP, CD14, IL-10, IL-1ß, IL-6, IL-8, MMP-1, TLR4, TNFα, and TNFSF13B were collected before, during (55 km and 110 km checkpoints), and after (160 km) the ride. No overall significant differences were found between groups of finishing and nonfinishing horses with regard to inflammatory marker expression. There were, however, time point-specific differences in mRNA expression, and, in some cases, these were group-specific. The overall pattern was a profound, initial increase in expression of inflammatory markers at the 55 km checkpoint. Some markers remained elevated beyond this point, whereas others began to decrease toward preride levels. While this work identified some similarities with previously published works, intraride sampling revealed additional changes in inflammatory marker expression. As such, investigators working with endurance horses should consider the addition of intraride sampling, when possible, to ensure that significant but short-lived changes in mRNA expression are not missed.

Evaluation of potential predictor variables for PCR assay diagnosis of Anaplasma phagocytophilum infection in equids in Northern California.

OBJECTIVE To identify clinical or clinicopathologic variables that can be used to predict a positive PCR assay result for Anaplasma phagocytophilum infection in equids. ANIMALS 162 equids. PROCEDURES Medical records were reviewed to identify equids that underwent testing for evidence of A phagocytophilum infection by PCR assay between June 1, 2007, and December 31, 2015. For each equid that tested positive (case equid), 2 time-matched equids that tested negative for the organism (control equids) were identified. Data collected included age, sex, breed, geographic location (residence at the time of testing), physical examination findings, and CBC and plasma biochemical analysis results. Potential predictor variables were analyzed by stepwise logistic regression followed by classification and regression tree analysis. Generalized additive models were used to evaluate identified predictors of a positive test result for A phagocytophilum. RESULTS Total lymphocyte count, plasma total bilirubin concentration, plasma sodium concentration, and geographic latitude were linear predictors of a positive PCR assay result for A phagocytophilum. Plasma creatine kinase activity was a nonlinear predictor of a positive result. CONCLUSIONS AND CLINICAL RELEVANCE Assessment of predictors identified in this study may help veterinarians identify equids that could benefit from early treatment for anaplasmosis while definitive test results are pending. This information may also help to prevent unnecessary administration of oxytetracycline to equids that are unlikely to test positive for the disease.

Practical Fluid Therapy and Treatment Modalities for Field Conditions for Horses and Foals with Gastrointestinal Problems.

With advances in technology and owner education, field management in equine veterinary medicine continues to evolve. Equine gastrointestinal disease is one of the most common types of emergencies evaluated by equine practitioners, and many of these patients can be effectively managed in the field. Although the equine veterinarian must make numerous decisions, fluid therapy, pain management, and antimicrobial use are 3 of the major choices that must be addressed when initiating field treatment of equine gastrointestinal disease. This article addresses the practical use of these 3 treatment categories that are essential to field practice.

Air pollution, weight loss and metabolic benefits of bariatric surgery: a potential model for study of metabolic effects of environmental exposures.

BACKGROUND: Emerging experimental evidence suggests that air pollution may contribute to development of obesity and diabetes, but studies of children are limited. OBJECTIVES: We hypothesized that pollution effects would be magnified after bariatric surgery for treatment of obesity, reducing benefits of surgery. METHODS: In 75 obese adolescents, excess weight loss (EWL), high-density lipoprotein (HDL) cholesterol, triglycerides, alkaline phosphatase (ALP) and hemoglobin A1c (HbA1c ) were measured prospectively at baseline and following laparoscopic adjustable gastric banding (LAGB). Residential distances to major roads and the average two-year follow-up exposure to particulate matter <2.5 µm (PM2.5 ), nitrogen dioxide (NO2 ) and ozone were estimated. Associations of exposure with change in outcome and with attained outcome two years post-surgery were examined. RESULTS: Major-roadway proximity was associated with reduced EWL and less improvement in lipid profile and ALP after surgery. NO2 was associated with less improvement in HbA1c and lower attained HDL levels and change in triglycerides over two years post-surgery. PM2.5 was associated with reduced EWL and reduced beneficial change or attained levels for all outcomes except HbA1c . CONCLUSIONS: Near-roadway, PM2.5 and NO2 exposures at levels common in developed countries were associated with reduced EWL and metabolic benefits of LAGB. This novel approach provides a model for investigating metabolic effects of other exposures.

Ability of clinicopathologic variables and clinical examination findings to predict race elimination in endurance horses.

OBJECTIVE To compare results of point-of-care laboratory testing with standard veterinary clinical examination findings at a single time point during endurance competition to identify horses at risk for elimination. ANIMALS 101 endurance horses participating in the 2013 Western States 160-km (100-mile) endurance ride. PROCEDURES At the 58-km checkpoint, blood samples were collected from all horses. Samples were analyzed for pH, Pco2, base excess, anion gap, PCV, and whole blood concentrations of sodium, potassium, chloride, total carbon dioxide, BUN, glucose, and bicarbonate. Corrected electrolyte and PCV values were calculated on the basis of plasma total protein concentration. Immediately following the blood sample collection, each horse underwent a clinical examination. In addition to standard examination variables, an adjusted heart rate was calculated on the basis of the variable interval between entry into the checkpoint and heart rate recording. A combination of stepwise logistic regression, classification and regression tree analysis, and generalized additive models was used to identify variables that were associated with overall elimination or each of 3 other elimination categories (metabolic elimination, lameness elimination, and elimination for other reasons). RESULTS Corrected whole blood potassium concentration and adjusted heart rate were predictive for overall elimination. Breed, plasma total protein concentration, and attitude were predictive for elimination due to metabolic causes. Whole blood chloride concentration and corrected PCV were predictive for elimination due to lameness. Corrected PCV was predictive for elimination due to other causes. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that for horses in endurance competition, a combination of breed and clinical examination and laboratory variables provided the best prediction of overall elimination.

Disease associated with equine coronavirus infection and high case fatality rate.

BACKGROUND: Equine coronavirus (ECoV) is associated with clinical disease in adult horses. Outbreaks are associated with a low case fatality rate and a small number of animals with signs of encephalopathic disease are described. OBJECTIVES: The aim of this study is to describe the epidemiological and clinical features of two outbreaks of ECoV infection that were associated with an high case fatality rate. ANIMALS: 14 miniature horses and 1 miniature donkey testing fecal positive for ECoV from two related disease outbreaks. METHODS: Retrospective study describing the epidemiological findings, clinicopathological findings, and fecal viral load from affected horses. RESULTS: In EcoV positive horses, 27% (4/15) of the animals died or were euthanized. Severe hyperammonemia (677 µmol/L, reference range ≤ 60 µmol/L) was identified in one animal with signs of encephalopathic disease that subsequently died. Fecal viral load (ECoV genome equivalents per gram of feces) was significantly higher in the nonsurvivors compared to animals that survived (P = .02). CONCLUSIONS AND CLINICAL IMPORTANCE: Equine coronavirus had a higher case fatality rate in this group of miniature horses than previously reported in other outbreaks of varying breeds. Hyperammonemia could contribute to signs of encephalopathic disease, and the fecal viral load might be of prognostic value in affected horses.

Salmonella spp. fecal shedding detected by real-time PCR in competing endurance horses.

Fecal shedding of Salmonella spp. was recently documented in 8% of endurance horses presented to equine referral centers for colic. Previous studies have documented fecal shedding of Salmonella spp. in as few as 0.8% of the general horse population, although horses with colic appear to be at higher risk. Fecal Salmonella spp. shedding before and after endurance horse competitions has not been evaluated. Fecal samples were collected from 204 horses during three separate 100 mile endurance competitions. Following incubation in selenite broth, 289 fecal samples were tested by real-time PCR analysis for Salmonella spp. Only one post-race sample (0.5% tested positive for Salmonella spp. in this study and no pre-race sample was available from this horse. Results suggest that fecal shedding of Salmonella spp. is uncommon in endurance horses during competitions. Further research is needed to confirm and identify the source of Salmonella spp. infection in endurance horses with colic requiring treatment at referral centers.

Clinical, hematologic, and electrolyte changes with 0.9% sodium chloride or acetated fluids in endurance horses.

OBJECTIVE: To describe the clinical and laboratory changes associated with the use of IV0.9% sodium chloride and a commercially available acetated fluid (CAF) to treat endurance horses requiring emergency medical treatment. DESIGN: Randomized, controlled clinical trial from 2007 to 2010. SETTING: Emergency treatment centers of the Western States 100-mile (220 km) endurance ride. ANIMALS: Twelve horses requiring emergency medical treatment in the form of IVfluids completed the study. INTERVENTIONS: Horses were assigned to either the 0.9% sodium chloride group (6 horses) or CAF group (6 horses) and received a total of 20 L of fluid. Clinical, hematologic, and electrolyte data were collected prior to and during fluid therapy. MEASUREMENTS AND MAIN RESULTS: As compared to results prior to fluid therapy, horses treated with 0.9% sodium chloride had a decrease in heart rate (P < 0.01), PCV (P < 0.001), total plasma protein (TPP) (P < 0.001), and the sodium-chloride difference (P < 0.05). These horses also had an increase in plasma chloride (P < 0.01) and sodium (P < 0.01) concentrations. Horses treated with CAF showed a decrease in PCV (P < 0.01) and TPP (P < 0.001). CONCLUSIONS: These findings should aid in the design a larger clinical trial to provide further clarification on the effects of type of fluid therapy on clinical and biochemical parameters in endurance horses. The use of 0.9% sodium chloride may not be ideal for the emergency management of endurance horses as it was associated with an increase in plasma chloride concentration.

Pulse pressure variation and systolic pressure variation in horses undergoing general anesthesia.

INTRODUCTION: Changes in arterial pressure due to respiratory phases have been used to predict fluid responsiveness in a number of species and pulse pressure variation (PPV) and systolic pressure variation (SPV) are commonly used. The relationship between PPV and SPV has not been described in horses. OBJECTIVES: To describe and compare PPV and SPV values of horses under general anesthesia. METHODS: Twenty-six horses undergoing general anesthesia and receiving mechanical ventilation were enrolled in the study. Recordings of maximal and minimal values of pulse pressure and systolic pressure were calculated every 15 minutes throughout surgery. RESULTS: Initial PPV was 15.6% (7.9, 33.8) and decreased over the first 30 minutes to 10.7 ± 7.2% (P = 0.03). Initial SPV was 10.3 ± 2.6% and decreased over the first 30 minutes to 7.3 ± 3.3% (P = 0.004). PPV and SPV had a correlation coefficient of 0.52 (P < 0.0001) and a 95% limits of agreement from -7.1% to 14.4%. CONCLUSION: PPV and SPV measurements in horses do not have strong agreement.

Colic in competing endurance horses presenting to referral centres: 36 cases.

REASONS FOR PERFORMING STUDY: Colic is a common reason for elimination from equine endurance competitions and has recently been identified as the leading cause of mortality in this group of horses. Hydration and electrolyte derangements are often severe, but are probably related to endurance exercise and not necessarily the episode of colic. Better understanding of the causes of colic and the expected outcome is needed to guide treatment decisions in endurance horses. OBJECTIVES: To describe the history, case details, clinical examination, laboratory, treatment and outcomes for horses presenting to equine referral centres for treatment of colic associated with endurance competition and to identify variables associated with prolonged hospitalisation. METHODS: Thirty-six horses from 2 equine referral centres were included in the analysis. In addition to descriptive statistics, Cox proportional hazards models were used to evaluate factors associated with length of hospitalisation. RESULTS: A diagnosis of open or ileus was made in the majority of horses (56%). Salmonellosis and enteritis (Salmonella negative) were also recognised (16%). Exploratory abdominal surgery was performed in 5 of the horses. Only one of 36 horses did not survive to discharge. Previous eliminations from competition (negative association) and total i.v. fluids within the first 24 h (positive association) of admission were both associated with length of hospitalisation. CONCLUSIONS: Endurance horses with colic typically respond to medical treatment but in some cases hospitalisation may be prolonged. The role of Salmonella infections in endurance horses with colic requires further research. POTENTIAL RELEVANCE: Despite potentially severe clinical and laboratory derangements, equine practitioners should make owners aware that the prognosis for competing endurance horses with colic is good when treated appropriately.

Determination of body water compartments in neonatal foals by use of indicator dilution techniques and multifrequency bioelectrical impedance analysis.

OBJECTIVE: To determine values for total body water (TBW), extracellular fluid volume (ECFV), intracellular fluid volume (ICFV), and plasma volume (PV) in healthy neonatal (< 24 hours old) foals and to create a multifrequency bioelectrical impedance analysis (MF-BIA) model for use in neonatal foals. ANIMALS: 7 healthy neonatal foals. PROCEDURES: Deuterium oxide (0.4 g/kg, IV), sodium bromide (30 mg/kg, IV), and Evans blue dye (1 mg/kg, IV) were administered to each foal. Plasma samples were obtained following an equilibration period, and the TBW, ECFV, ICFV, and PV were calculated for each foal. An MF-BIA model was created by use of morphometric measurements from each foal. RESULTS: Mean ± SD values were obtained for TBW (0.744 ± 0.024 L/kg), ICFV (0.381 ± 0.018 L/kg), ECFV (0.363 ± 0.014 L/kg), and PV (0.096 ± 0.015 L/kg). The 95% limits of agreement between the MF-BIA and indicator dilution techniques were within ± 2 L for TBW and ECFV. CONCLUSIONS AND CLINICAL RELEVANCE: Fluid volumes in neonatal foals were found to be substantially larger than fluid volumes in adult horses. Multifrequency bioelectrical impedance analysis may be a useful technique for predicting TBW, ICFV, and ECFV in neonatal foals.

A comparison of hypertonic (7.2%) and isotonic (0.9%) saline for fluid resuscitation in horses: a randomized, double-blinded, clinical trial.

BACKGROUND: Hypertonic saline solution (7.2%) (HSS) can quickly replace intravascular volume deficits. HSS more recently has been advocated in the treatment of traumatic brain injury, but its use in dehydrated patients remains controversial. HYPOTHESIS: Hypertonic saline solution will show a significant improvement in both clinical and laboratory hydration parameters as compared to isotonic (0.9%) saline solution (ISS). ANIMALS: Endurance horses eliminated from the 2009 Western States 100-mile (220-km) endurance ride and requiring IV fluid therapy were eligible for enrollment in the study. METHODS: Twenty-two horses were randomly assigned to receive 4 mL/kg of either HSS or ISS along with 5 L lactated Ringer's solution (LRS). After this bolus, horses were treated with additional LRS in varying amounts. Blood and urine samples were collected before, during, and after treatment. Data were compared using 2-way ANOVA with repeated measures. RESULTS: As compared to ISS, HSS horses showed greater decreases in PCV (P = .04), total protein (P = .01), albumin (P = .01), and globulin (P = .02) concentrations. HSS horses showed greater increases in sodium and chloride (P < .001) as compared to ISS horses. Horses receiving HSS had a shorter time to urination (P = .03) and lower specific gravity (P < .001) than those receiving ISS. CONCLUSIONS: Results of this study indicate that HSS may provide faster restoration of intravascular volume deficits than ISS in endurance horses receiving emergency medical treatment. More marked electrolyte changes should be expected with HSS, however, and additional fluids after HSS administration likely are needed.

Risk factors for the elimination of endurance horses from competition.

OBJECTIVE: To identify risk factors such as signalment, previous competition miles completed, ride characteristics, and physical examination variables associated with the elimination of horses during endurance competitions. DESIGN: Retrospective observational study. SAMPLE: Veterinary records for 3,493 endurance horse competition starts. PROCEDURES: Records were requested of all sanctioned 2007 endurance horse competitions in the United States. Only rides that provided data from all horses were included. The horse's signalment, previous endurance competition record, specific ride characteristics, weight division (ie, based on rider's weight with tack), and physical examination variables throughout the ride were included for analysis. Examination variables were separated into abnormalities occurring prior to the start of the ride, during the first half of the ride, and during the second half of the ride. Multivariate logistic regression was used to identify risk factors for overall elimination and elimination subcategories (lameness and metabolic). RESULTS: Specific breeds, the heavyweight division, and distance of the ride were all associated with an increased risk of elimination. A variety of examination variables prior to the start of the ride and during the ride were associated with elimination and included heart rate, cardiac recovery index, and abnormal gastrointestinal sounds. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that specific risk factors were associated with elimination of horses from endurance competitions. These factors may be used to help identify horses at higher risk for elimination and prevent morbidity associated with competition.